Abstract: Flocculation settlement and dewatering through filtration are common methods used for treating slime water. The efficiency of flocculation directly impacts the dewatering process of coal slime. This paper introduces a novel technology to enhance the flocculation and dewatering process of coal slime water by utilizing ultrasonically modified cationic polyacrylamide (CPAM). The characteristics of CPAM solutions pretreated with ultrasonic treatment for different durations were examined using a rheometer. The impact of ultrasonically modified flocculants on the settling of coal slime water was analyzed through settlement and turbidity tests. Floc properties of various modified CPAMs in the treatment of slime water were observed using the focused beam reflectance measurement system and the particle observation system. Furthermore, a correlation was established between the floc properties and the characteristics of the filter cake formed during the filtration of coal slime water. Experimental results indicate that after 40 seconds of ultrasonic treatment, CPAM demonstrates the most effective slime flocculation with the lowest supernatant turbidity, approximately 180 NTU. Under these conditions, coal slime filtration occurs at the fastest rate, reducing filtration time by about 25 seconds compared to cases without ultrasonic treatment. Additionally, the moisture content of the filter cake obtained under these conditions is the lowest, around 29%. This phenomenon can be attributed to the formation of multi−molecular−weight polymers in the CPAM solution following 40 seconds of sonication. Low−molecular−weight agents gradually aggregate coal slime particles into small flocs, while high−molecular−weight agents further link these small flocs together. Coal slime particles become tightly bound within the polymer matrix through a complex system of multi−component polymers. As the flocs settle, they create a denser structure and sedimentary bed. This sediment layer, composed of dense flocs, offers lower filtration resistance, enhancing filtration speed, and resulting in a reduced moisture content in the filter cake post−filtration.